Well, I think ya'll have made my decision for me, lol. The humps are coming off. I know what ya mean about taking the timing away and I don't really like it either but just trying to be safe. Man, this forum is awesome. I have messed with cars since I was just a young teenager, my father raced dirt track and taught me alot, and been a mechanic my whole working career but I have learned so much from this forum.

Speaking for myself, I learn things on a regular basis- there are some very knowledgeable people here, for sure.

Cool that your Dad raced and took the time to teach you along the way. I also learned at my Father's knee, he knew so much. I miss him every day.

These heads are all similar. Prolly not a 5 hp difference between them as long as the are prepared the same. The 041 is supposed to have a little more meat under the spring seat and is "stealthy" in that it doesn't have the double hump identifier.

Pay attention to the compression ratio- a 64cc chamber on a 400 SBC w/flat tops and a tight quench can exceed 11.5:1- higher than pump gas will allow w/o detonation. A 22cc dished piston will put you at about 9.75:1, the absolute limit I would recommend using iron heads- and even then the cam has to be chosen carefully so the dynamic compression ratio isn't too high.

You should CC the heads to be sure that each pair are the same, and that none were milled excessively. Even if they are as cast and never been milled, the chamber volumes can vary from published figures.

Thank you for the great info and for the links. I pulled the tunnel ram off and actually had 4 lifters that were bad, just not bleeding down as fast like that one. I checked my cam lobes and they checked good and also looked very nice and broken in by looking through the lifter bores. I used Isky cam lube on the flats of the lifters, after soaking them in 30W oil overnight, and put em in and got the Stealth intake on I'm gonna run temporarly. I had to stop as the Ala. vs LSU game was about to start, watching it now lol. I hope to get the impala finished up tomorrow and get started on the motor swaps i've got lined up. I wrapped the 400 up and plan on using it in an S10 build I plan to do soon. I will be reading about CR before I make my decision on which way to go.

Thank you for the great info and for the links. I pulled the tunnel ram off and actually had 4 lifters that were bad, just not bleeding down as fast like that one. I checked my cam lobes and they checked good and also looked very nice and broken in by looking through the lifter bores. I used Isky cam lube on the flats of the lifters, after soaking them in 30W oil overnight, and put em in and got the Stealth intake on I'm gonna run temporarly. I had to stop as the Ala. vs LSU game was about to start, watching it now lol. I hope to get the impala finished up tomorrow and get started on the motor swaps i've got lined up. I wrapped the 400 up and plan on using it in an S10 build I plan to do soon. I will be reading about CR before I make my decision on which way to go.

Wow- 4 bad lifters. Just a word of caution: You do realize the chances are very, very good that at least a few of the cam lobes are worn abnormally. I would feel a LOT better if you'd bite the bullet now and put a new cam and lifters in it before the lobes go really bad and you get ground up cam and lifters circulated all through the engine- which can take the bearings and journals out, too. Meaning new bearings, a turned crank and a complete tear down to clean the trash out of the engine.

Here's a link to an online cam degree calculator that you can use to determine the intake closing angle. Using this in conjunction with the United Engine & Machine online DCR calculator will give a more accurate dcr than just using the generic "add 15 degrees to the duration at 050" in the dcr calculations. This gives almost identical results as the Pat Kelley calculator. Wallace Racing - Cam Degree Calculator

Wow- 4 bad lifters. Just a word of caution: You do realize the chances are very, very good that at least a few of the cam lobes are worn abnormally. I would feel a LOT better if you'd bite the bullet now and put a new cam and lifters in it before the lobes go really bad and you get ground up cam and lifters circulated all through the engine- which can take the bearings and journals out, too. Meaning new bearings, a turned crank and a complete tear down to clean the trash out of the engine.

Well, now you got me nervous, lol. I'm pulling it back down and replacing the cam. What I mean by the 4 bad lifters is they wouldn't open the valves all the way, like they weren't getting oil and pumping up or something but they were getting oil and lots of it. I took 2 of em apart just to verify. I checked all the cam lobes with my dial indicator and they are all checking good, turned the motor over 2 revolutions. Shined a light through the lifter bores and all the lobes look like they broke in great. I just took it as a bad batch of lifters. I'm ordering a new cam this morning. I've thought, well, what would dad have done and it came to me, heck, he would have pulled the whole motor down "just to be on the safe side" as he would say, lol. I really need the space in my garage pretty quick but I also really really need the little money in my wallet not to mention wasting my parts.

Here's a link to an online cam degree calculator that you can use to determine the intake closing angle. Using this in conjunction with the United Engine & Machine online DCR calculator will give a more accurate dcr than just using the generic "add 15 degrees to the duration at 050" in the dcr calculations. This gives almost identical results as the Pat Kelley calculator. Wallace Racing - Cam Degree Calculator

When your dealing with 4 bad lifters,you want to treat the cause and not the effect,the four bad lifters.Deductive logic says there is a reason behind why four lifters when bad.Question if you have a blocked oil gallery.But to find the root cause is going to prevent it happening again with the new set of lifters.Those lifters once preloaded have to turn in their bores while the engine is being turned over and you can check that with the intake off.Also the lobes and just the way they look really doesn't mean much.What they measure as will tell apart of the story.

When your dealing with 4 bad lifters,you want to treat the cause and not the effect,the four bad lifters.Deductive logic says there is a reason behind why four lifters when bad.Question if you have a blocked oil gallery.But to find the root cause is going to prevent it happening again with the new set of lifters.Those lifters once preloaded have to turn in their bores while the engine is being turned over and you can check that with the intake off.Also the lobes and just the way they look really doesn't mean much.What they measure as will tell apart of the story.

Thank you for your input. I marked a small line from the block to lifter on all the lifters with a white welders pencil and made sure all of them were turning before I checked with my dial indicator. Everything is oiling great as far as I can tell but I only took 3 of the lifters apart. The motor ran great it just developed a lifter tick from the #4 exh. I adjusted it twice and one time for my buddy, to show him what was going on, and it would adjust but after letting it sit for about 10min. you could go back and check it by hand and the rocker would be sloppy loose again. I mean just sittin there, not starting the motor. I ordered a new cam of the exact specs just a little bit ago and it should be here Tuesday so I will let you know what happens in about a week as I'm disabled and have to do everything very slow, lol. I built this motor myself and after checking everything I opted to not have any machine work done. I honed the cylinders, washed and blew out all the passages, cleaned the ring grooves etc..., lapped the valves and installed positive lock seals, correct springs etc... broke the cam in by the instructions from Isky etc etc etc... I used Clevite bearings and Hastings rings, Melling HV55 pump, Pete Jackson gear drive, had to machine the back pin on the drive gear where it touches the block but you know what I'm saying. In my opinion I built the motor just like I was taught years ago and to the best of my ability. When I changed the oil after breaking in the cam after cool down I ran a magnet through the oil and by the magnet and by eye the oil looked great, felt great etc... Nothing abnormal I should say, lol. Once again, Thank you for your input.

I applaud you for everything you have done.I'm not being critical.What caught my eye is gear drives can be hard on cams,cam bearings,etc.They where at one time a favorite at one time and what was found they really didn't work well for street use and had limited race applications where changing cam timing often was needed.Since the gear drives came out other systems have evolved.

Well, now you got me nervous, lol. I'm pulling it back down and replacing the cam. What I mean by the 4 bad lifters is they wouldn't open the valves all the way, like they weren't getting oil and pumping up or something but they were getting oil and lots of it. I took 2 of em apart just to verify. I checked all the cam lobes with my dial indicator and they are all checking good, turned the motor over 2 revolutions. Shined a light through the lifter bores and all the lobes look like they broke in great. I just took it as a bad batch of lifters. I'm ordering a new cam this morning. I've thought, well, what would dad have done and it came to me, heck, he would have pulled the whole motor down "just to be on the safe side" as he would say, lol. I really need the space in my garage pretty quick but I also really really need the little money in my wallet not to mention wasting my parts.

There's a reason your Father had the opinions he did on these things- and you are wise to follow his lead on such matters. I cannot help but think you've chosen the best and safest path. When the cost associated w/changing the cam and lifters now is compared to the possible costs involved w/chancing it, the choice becomes even more clear IMHO.

Some good info on breaking in a flat tappet cam along w/other tips, etc, can be read here.

There's a reason your Father had the opinions he did on these things- and you are wise to follow his lead on such matters. I cannot help but think you've chosen the best and safest path. When the cost associated w/changing the cam and lifters now is compared to the possible costs involved w/chancing it, the choice becomes even more clear IMHO.

Some good info on breaking in a flat tappet cam along w/other tips, etc, can be read here.

WOW! Thanks alot for the links and the advice. You are exactly right on the costs involved and I am finding the reasons Dad did alot of things the older I get. I think one of my buddy's is gonna do a motor job for me as it's gonna take me a little bit before I will have my garage freed up. I did find out something today that I still can't believe, lol. I have a 1969 DZ302! A few months ago I bought a square body S10 off a young feller just for the motor and trans. He had wrecked it pretty bad, wiped the whole right side out and bent the frame a little, and was gonna crush it. It has a " '69 model 350 in it with double humps" he said. Well, after looking at it and hearing it run, I bought it. I have quite a collection of older Chevy parts and try to save everything I can from the crusher that is GM plus I wanted the drivetrain and motor for another project I have lined up. Long story short I got the truck where I felt it was safe to take a short drive, after I got it home, and got in it a little and thought, man, this thing does have the power for a stock 350 that had who knows how many miles on it as it has never been apart from what I can tell. So today I jacked her up and got under and looked and sure enough, it has a completely round end on the crank. You know what that means, steel crank! So I finally got myself up from underneath, grabbed a rag, brass brisltled carb cleaning brush and some purple power and cleaned the pad off on the front right side of the block. Guess what, last 2 digits are DZ!! I can't believe it. I have never actually seen one in person much less owned one. Tomorrow before I start on the Impala I'm draining the old anti-freeze out and puttin new in for winter. I'm not taking any chances, I never do with anything anyway when it comes to a motor freezing, but it makes me feel good to know that it will feel better with fresh coolant, oil and a Wix filter, lol. I feel like a big ole kid right now.

WOW! Thanks alot for the links and the advice. You are exactly right on the costs involved and I am finding the reasons Dad did alot of things the older I get. I think one of my buddy's is gonna do a motor job for me as it's gonna take me a little bit before I will have my garage freed up. I did find out something today that I still can't believe, lol. I have a 1969 DZ302! A few months ago I bought a square body S10 off a young feller just for the motor and trans. He had wrecked it pretty bad, wiped the whole right side out and bent the frame a little, and was gonna crush it. It has a " '69 model 350 in it with double humps" he said. Well, after looking at it and hearing it run, I bought it. I have quite a collection of older Chevy parts and try to save everything I can from the crusher that is GM plus I wanted the drivetrain and motor for another project I have lined up. Long story short I got the truck where I felt it was safe to take a short drive, after I got it home, and got in it a little and thought, man, this thing does have the power for a stock 350 that had who knows how many miles on it as it has never been apart from what I can tell. So today I jacked her up and got under and looked and sure enough, it has a completely round end on the crank. You know what that means, steel crank! So I finally got myself up from underneath, grabbed a rag, brass brisltled carb cleaning brush and some purple power and cleaned the pad off on the front right side of the block. Guess what, last 2 digits are DZ!! I can't believe it. I have never actually seen one in person much less owned one. Tomorrow before I start on the Impala I'm draining the old anti-freeze out and puttin new in for winter. I'm not taking any chances, I never do with anything anyway when it comes to a motor freezing, but it makes me feel good to know that it will feel better with fresh coolant, oil and a Wix filter, lol. I feel like a big ole kid right now.

I agree w/Vinnie- if that block isn't a restamp and has the original suffix code, etc. on the pad (which would indicate the decks haven't been cut much, if at all), and if it has a standard bore, you have got yourself a heck of a find!!! Even if it's been bored, killer deal!

Because the guy you bought it from made no big deal out of it being a DZ block, likely no one made a big deal to him about it when he bought it- so either it's gonna be a legit block or a really obvious restamp.

Factory suffix codes have the digits/letters evenly spaced and look uniform because of being 'gang stamped' instead of each digit being individually stamped, and none are higher or lower than the digit next to it. A really obvious restamp, complete w/punch marks all over the area AND two different styles of the number "1", is at the bottom of this post. Also the partial VIN code line of digits that usually accompanies the suffix line is the same way- but the two lines are almost never even to each other because they are stamped at different times/places.

I'm sure you'll be researching this to the n'th degree, I hope that it's legit and that you got an early Christmas present!!

nice score,havent seen many DZ blocks,hope its still standard bore.probably make some money on it

It looks to be like it's all still stock, never opened up and if it has been it's been awhile. I won't sell it as I try to save as much old chevy stuff as I can. I plan on leaving each one of my nephews, I have 3, a "60's model GM car or truck and they can split all the goodies I have collected. I have built my oldest nephews truck, he is 5yrs. old, 1969 SWB .040 over flat top 454, the engine in it is my avatar. My 1968 Impala I'm building is for the middle one, 3 yrs. old. I have been looking for a '68-'69 Nova to build for the youngest, almost 2 yrs. old.

I agree w/Vinnie- if that block isn't a restamp and has the original suffix code, etc. on the pad (which would indicate the decks haven't been cut much, if at all), and if it has a standard bore, you have got yourself a heck of a find!!! Even if it's been bored, killer deal!

Because the guy you bought it from made no big deal out of it being a DZ block, likely no one made a big deal to him about it when he bought it- so either it's gonna be a legit block or a really obvious restamp.

Factory suffix codes have the digits/letters evenly spaced and look uniform because of being 'gang stamped' instead of each digit being individually stamped, and none are higher or lower than the digit next to it. A really obvious restamp, complete w/punch marks all over the area AND two different styles of the number "1", is at the bottom of this post. Also the partial VIN code line of digits that usually accompanies the suffix line is the same way- but the two lines are almost never even to each other because they are stamped at different times/places.

I'm sure you'll be researching this to the n'th degree, I hope that it's legit and that you got an early Christmas present!!

Thanks for the kind words. I'm gonna pull the motor and trans just as soon as I get my Impala back together, I'm shooting for next week lol. I will be able to get a better look at the stamping that way. I had never thought about someone restamping a block. I'm keeping my fingers crossed and will post a picture of the stamping when I get it out and cleaned up better. Some people amaze me at how they can come up with a way to get over on people. I spent about all day on my Impala yesterday. Got almost down to pulling the cam when my body stopped going. I'm going to try to get the cam out and everything cleaned today but I just have to see how my body does. The new cam is suppose to be here today. See, I'm disabled, I had a 5000lb. forklift fall on me June 13 2007, I was a mechanic for a forklift repair company, and I'm only able to do so much BUT, I am so very thankful the good Lord let's me do what I am able to do. I take one day at a time and try and make the best out of my situation as I could be in a heck of alot worse shape, plus, I love wrenchin, lol.

Last edited by Camaro_Nut2001; 11-06-2012 at 08:10 AM.
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